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arXiv 1010.1872cs.LO
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基于SMT求解的阵列系统向后可达性:终止性与不变综合

Backward Reachability of Array-based Systems by SMT solving: Termination and Invariant Synthesis

Silvio Ghilardi, Silvio Ranise

摘要:

无限状态系统的安全性可以通过一个向后可达过程来检验。对于某些类型的系统,可以证明过程的终止,从而得出安全问题的可判定性。虽然向后可达性是属性导向的,但它可以不必要地探索系统的状态空间的(大)部分,这些部分不需要验证所考虑的安全属性。为了避免这种情况,可以使用不变量来大幅修剪搜索空间。事实上,问题是要猜测这样合适的不变量。在本文中,我们提出了一个完全声明性和符号化的方法来机械化的向后可达的无限状态系统操纵数组的可满足性模理论解决。理论用于指定拓扑结构和由系统操作的数据。我们确定的理论,以确保向后可达性的终止的充分条件,我们显示的完整性不变的合成方法(作为对偶的向后可达性),再次,在适当的假设下的理论。我们还提出了一个务实的方法交错不变的合成和向后可达性,使一组向后可达状态的不动点更容易获得。最后,我们讨论了算法,使我们能够得到一个实现的技术在模型检查MCMT,显示显着的速度加快了一组重要的安全问题,从各种来源提取。

英文摘要:

The safety of infinite state systems can be checked by a backward reachability procedure. For certain classes of systems, it is possible to prove the termination of the procedure and hence conclude the decidability of the safety problem. Although backward reachability is property-directed, it can unnecessarily explore (large) portions of the state space of a system which are not required to verify the safety property under consideration. To avoid this, invariants can be used to dramatically prune the search space. Indeed, the problem is to guess such appropriate invariants. In this paper, we present a fully declarative and symbolic approach to the mechanization of backward reachability of infinite state systems manipulating arrays by Satisfiability Modulo Theories solving. Theories are used to specify the topology and the data manipulated by the system. We identify sufficient conditions on the theories to ensure the termination of backward reachability and we show the completeness of a method for invariant synthesis (obtained as the dual of backward reachability), again, under suitable hypotheses on the theories. We also present a pragmatic approach to interleave invariant synthesis and backward reachability so that a fix-point for the set of backward reachable states is more easily obtained. Finally, we discuss heuristics that allow us to derive an implementation of the techniques in the model checker MCMT, showing remarkable speed-ups on a significant set of safety problems extracted from a variety of sources.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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